The remains of King Richard III were lost for centuries beneath a parking lot in Leicester, England, until archeologists discovered the site in Sept. 2012 and later confirmed the match. But other mysteries have been found, including a double coffin thought to have been sealed more than 100 years before Richard was buried.

Archaeologists returned to the Grey Friars monastery site in early July for more study. After several weeks of excavation, eight people lifted the lid off of a heavy coffin made of stone on July 23. They discovered that an inner coffin made of lead was sealed within the outer stone coffin.

The 7-foot-long stone coffin was thought to have been sealed in the 13th or 14th century. After its opening, the lead inner coffin was moved to the University of Leicester for researchers to analyze how to access it without damaging the remains inside.

Archaeologists believe the double coffin indicates a "high-status burial" and may be one of the monastery's founders, either Peter Swynsfeld (died in 1272) or William of Nottingham (died in 1330). A third option could be Sir William de Moton of Peckleton, a 14th century knight.

We still don't know who is inside - so there is still a question mark over it… None of us in the team have ever seen a lead coffin within a stone coffin before. We will now need to work out how to open it safely as we don't want to damage the contents when we are opening the lid.
– Mathew Morris, University of Leicester Archaeological Services

The excavation leader said the double coffin discovery was "as exciting as finding Richard III."